Paper coating machine

Abstract

A highly compact machine for applying an attractive protective coating to a paper web that passes through a printing press is located between the last press stand and the dryer of the printing press, and to enable the machine to receive the web, the printing press is provided with an apparatus for directing the web back to the print stands and the machine after the web passes through the dryer. The machine includes upper and lower blanket cylinders, a plate cylinder contacting the lower blanket cylinder, and an oscillating cylinder below the plate cylinder. In addition the coating machine includes a pan containing a coating fluid and a pan roller, the surface of which rotates through the fluid in the pan to lift it out of the pan. A metering roller revolves close to the pan roller to remove excess fluid from the pan roller which thereupon transfers the fluid to a form roller. That form roller runs against the oscillating cylinder and transfers the fluid to the oscillating cylinder. Another form roller contacts both the oscillating cylinder and the plate cylinder, and transfers the fluid to the plate cylinder. The plate cylinder delivers the fluid to the lower blanket cylinder which in turn applies it to the web. The plate cylinder carries a cylindrical plate which is normally continuous, but may be left with a cutout or void so that a small portion of the web is left uncoated with each revolution of the blanket cylinder.

What is claimed is: 
     
       1. In combination with a printing press including at least one print stand where a printed image is applied to a web and a dryer located beyond the last print stand and including a first drying chamber through which the web passes to dry ink that is applied to it at the print stands, the improvement comprising: deflecting means for directing the web back toward the last print stand after the web passes through the dryer, and a coating unit physically interposed between the last print stand and the dryer, said coating unit comprising: first and second blanket cylinders which are located adjacent to each other so as to form a nip between them, with the nip being located such that the web passes into it after passing through the dryer and being directed back toward the last print stand by the deflecting means, a plate cylinder located adjacent to the second blanket cylinder and carrying a generally cylindrical plate which bears against the surface of the second blanket cylinder, and transfer means for applying a coating fluid to the outwardly exposed surface of the plate, whereby the coating fluid is transferred to the second blanket cylinder and thence to the web as the web passes through the nip. 
     
     
       2. The combination according to claim 1 wherein the plate of the plate cylinder has a cutout, so that when the plate transfers the fluid to the second blanket cylinder, a region exists on the second blanket cylinder that is free of the fluid, whereby a portion of the web is not coated with fluid. 
     
     
       3. The combination according to claim 1 wherein the dryer includes a second drying chamber located adjacent to the first drying chamber; and wherein the combination further comprising means for directing the web into the second drying chamber after it passes through the nip between the first and second blanket rollers of the coating unit. 
     
     
       4. The combination according to claim 3 wherein the second drying chamber of the dryer is located above and spaced slightly from the first drying chamber, and the means for directing the web back to the nip between the blanket cylinders of the coating unit directs the web into the space between the first and second drying chambers. 
     
     
       5. The combination according to claim 1 and further comprising a diverting stand located between the last print stand and the dryer and being configured to permit the web to pass through it, and wherein the coating unit is mounted adjacent to the diverting stand. 
     
     
       6. The combination according to claim 1 wherein the transfer means of the coating unit comprises an oscillating cylinder which rotates such that it has the same surface speed as the plate cylinder and further oscillates to and fro axially, a first form roller located between and contacting the oscillating roller and the plate of the plate cylinder; a pan for holding the coating fluid; and means for elevating the coating fluid from the pan to the oscillating cylinder. 
     
     
       7. The combination according to claim 6 wherein the means for elevating the fluid includes a pan roller which rotates within the pan and a second form roller that is normally along the pan roller and bears against the oscillating roller. 
     
     
       8. The combination according to claim 7 wherein the means for elevating the fluid further includes a metering roller which revolves close to the pan roller, yet is spaced from the pan roller, and is located such that it squeezes some coating fluid off of the pan roller before the pan roller delivers the fluid to the second form roller. 
     
     
       9. In combination with a succession of print stands through which a web of paper passes to have inked images applied to the web and a dryer through which the web also passes to dry the ink on the paper of the web, with the dryer being located beyond the last print stand, the improvement comprising: means for directing the web of paper back toward the last print stand after it passes through the dryer, and a machine located between the last print stand and the dryer for receiving the web and applying a coating fluid to the web after the web is directed back beyond the dryer so as to provide the paper with a protective coating, said machine comprising: a frame; upper and lower blanket cylinders mounted on the frame such that a nip exists between them for accepting the web; a plate cylinder mounted on the frame generally below the lower blanket cylinder and having a cylindrical plate that contacts the lower blanket cylinder; an oscillating cylinder mounted on the frame generally below and spaced from the plate cylinder and oscillating to and fro along its axis as it rotates; drive means for rotating the blanket, plate and oscillating cylinders such that they all have the same surface velocity; a pan for holding the coating fluid; a pan roller that rotates within the pan so that the coating fluid wets its surface; a first form roller mounted on the frame and being normally in contact with the cylindrical plate of the plate cylinder and the oscillating cylinder for transferring coating fluid from the oscillating cylinder to the cylindrical plate; and a second form roller mounted on the frame to normally rotate in close proximity to the pan roller and generally in contact with the oscillating cylinder for transferring coating fluid from the pan roller to the oscillating cylinder. 
     
     
       10. The combination according to claim 9 wherein the cylindrical plate of the plate cylinder is generally continuous, but contains a void so that plate cylinder will transfer the coating fluid to the blanket cylinder only in the generally continuous region thereof. 
     
     
       11. The combination according to claim 9 and further comprising means for moving the first form roller away from the plate cylinder. 
     
     
       12. The combination according to claim 9 and further comprising means for adjusting the spacing between the axis of rotation for the oscillating cylinder and the axis of rotation for the first form cylinder. 
     
     
       13. The combination according to claim 12 wherein the means for adjusting spacing includes bushings fitted around the ends of oscillating cylinder and having their exterior surfaces concentric to the axis of the oscillating cylinder, eccentric collars fitted around the bushings, and supports fitted around the eccentric collars and carrying the first form roller, whereby when the eccentric collars are turned, the spacing between the axes of the oscillating cylinder and first form roller will be varied. 
     
     
       14. The combination according to claim 13 wherein the supports are bell cranks, and further comprising means for rotating the bell cranks on the eccentric collars to separate the first form roller from the plate cylinder. 
     
     
       15. The combination according to claim 9 and further comprising means moving the second form roller away from the plate cylinder. 
     
     
       16. The combination according to claim 15 and further comprising means for adjusting the spacing between the axis of rotation for the oscillating cylinder and the axis of rotation for the second form cylinder. 
     
     
       17. The combination according to claim 16 wherein the means for adjusting spacing includes bushings fitted around the ends of oscillating cylinder, and having their exterior surfaces concentric to the axis of the oscillating cylinder, eccentric collars fitted around the bushings, and supports fitted around the eccentric collars and carrying the second form roller, whereby when the eccentric collars are turned, the spacing between the axes of the oscillating cylinder and second form roller will be varied. 
     
     
       18. The combination according to claim 17 wherein the supports are bell cranks, and further comprising means for rotating the bell cranks on the eccentric collars to separate the first form roller from the plate cylinder. 
     
     
       19. The combination according to claim 9 and further comprising a metering roller located adjacent to the pan roller for removing some coating fluid from a surface area of the pan roller before that surface area moves on to the second form roller where some of the coating fluid is transferred to the second form roller. 
     
     
       20. The combination according to claim 19 and further comprising means for moving the first form roller away from the plate cylinder and means for moving the second form roller away from the pan roller. 
     
     
       21. In combination with at least one print stand at which a printed image is applied to a web and a dryer located beyond the print stand in the path taken by the web and having a heated interior through which the web passes to dry the ink that is applied to it, the improvement comprising: first directing means for directing the web, after it passes through the heated interior of the dryer, back generally toward the print stand, and a coating unit generally interposed between the print stand and the dryer for receiving the web after it is directed back toward the print stand and applying a coating fluid to the web, the coating unit including a blanket roller over which the web passes with the roller revolving as the web moves over it and means for supplying the coating fluid to the blanket roller remote from the web so that the blanket roller will transfer the fluid to the web as the blanket roller revolves. 
     
     
       22. The combination according to claim 21 wherein the coating unit includes a second blanket roller which revolves with the first blanket roller and forms with the first blanket roller a nip through which the web passes. 
     
     
       23. The combination according to claim 21 and further comprising second directing means located downstream from the coating unit for directing the web, after it passes through the coating unit, back into the heated interior of the dryer. 
     
     
       24. The combination according to claim 23 wherein the dryer has first and second chambers arranged adjacent to each other and with a space between the two chambers, wherein the web between the print stand and the first directing means passes through the first chamber, wherein the web between the first directing means and the coating unit passes through the space, and wherein the web after the coating unit passes through the second chamber.